Nokia 3310

It'd still be charged

There’s an entire book dedicated to answering your question: The World Without Us.

The Wikipedia article I linked summarizes a lot of the book, but I recommend reading it since the details are fascinating.

TL;DR:

The longest-lasting evidence on Earth of a human presence would be radioactive materials, ceramics, bronze statues, and Mount Rushmore. In space, the Pioneer plaques, the Voyager Golden Record, and radio waves would outlast the Earth itself.

Almost certainly, depending on the time scale. Physical constructs will eventually break down, but the impact on the environment in total will likely be able to be deduced for millions of years.

For example, we already have a good record of the five previous mass extinction events, and can tie them directly to geological causes. On our current trajectory, a sixth wouldn't necessarily tie well to any other factors other than the activity of a dominant species. This is one of many factors in the proposed geological epoch of the anthropocene.

The stuff humans have left on the Moon and Mars would probably be good indicators.

I've heard that our nuclear impact will be seen for a very very long time from all the nuclear testing we did

And plastics

And our fertilizers

I would guess that things like massive landfill dumps would be almost impossible to wipe all trace of. There's no natural process that can collect that huge number of different chemical elements in such high amounts into a single location. So even if literally everything manmade has broken down to its consistent elements, the presence of a mile-wide radius plot of earth containing every solid element in the chart would be a clear indicator that an advanced civilization must have been there.

A very thin smear of exhaust fumes, long-chain hydrocarbons, and rare radioisotopes.

Also a very clear mass extinction event.

They will wonder why our entire civilisation was based around plastic bags.

Ironically, our best bet is probably our space junk. Leave as much of our stuff in space and on the moon as possible.

There will be strangely distributed concentrations of various materials in any sediment layer from our period, such as iron, copper, aluminum, hydrocarbons, and various minerals. A lot of these will be in relatively small areas and also laid out in clearly artificial geometric patterns, especially in straight lines.

Yes, even in millions of years, traces of human civilization should still be easily detectable by a future civilization. The geological record will contain many elements that don't occur naturally and would point to an industrial civilization. Some relics of human civilization will fossilize or otherwise be preserved. Finally, there will be well preserved human-made objects in space, either in high earth orbit or on the moon.

The nuclear waste will be radioactive for thousands of years, it will probably be radioactive longer than our current recorded history as a whole. Think about that, ever since humans started recording our history, our nuclear waste will be radioactive longer than that.

Depends entirely on how long until the "next intelligent species to arise" (no reason to expect it ever will)

I watched a special years ago about what would happen to our infrastructure, buildings, etc if humans just blinked out of existence. The show start off advancing time, touching on events as they might occur. The very last thing to withstand the test of time was Mount Rushmore, due to be carved from granite. Mount Rushmore would stick around for a very very very long time and would be the last trace of us. But that's just that one TV show special's opinion, but it sounds pretty.....solid to me.

Fertilizer is what I've heard.

Long after the weight of ages has ground our works and bones to scattered dust, the changes we've made to the nitrogen cycle will stick out in the geologic record.

The jump from base levels of nitrogen to the obviously unnaturally higher amounts that would remain in layers from our time just wouldn't have any explanation other than something did it on purpose. There's basically no way for that level of increase to occur in what is geologically the blink of an eye without industrial capacity. Or that's what I've heard.

Micro plastics in the earth.

There would be signs, but I don't think there is any guarantee that a new intelligent life form would care to look for such signs, or that they'd have the type of intelligence that would be able to interpret the signs of our existence and conclude that we had existed in their distant past.

At best, our existence would be one of several theories explaining abnormalities about the Earth that future intellectuals would argue about.

A layer of space trash floating around the planet

Any remaining Ice Sheets will have an accurate record of air emissions such as Carbon where the depth roughly equals the time since, and since just before the Industrial Revolution the amount of carbon emission shot up like the face of a cliff compared to the hundreds of millions of years before it.

The pyramids.

AOL and Compuserve CDs.

Just a wee microscopic layer of plastic in the geological sediment.

There's a few random projects that aim to store bulk data and human information in durable materials.

https://www.popsci.com/technology/5d-disc-stores-500-tb-of-data/

Professor Peter Kazansky, from the ORC, says: "It is thrilling to think that we have created the technology to preserve documents and information and store it in space for future generations. This technology can secure the last evidence of our civilisation: all we've learnt will not be forgotten."

I'm learning most of the articles are all based on this guy from 2013 until now it's still been in mostly research phase though proof of concepts have been done.

I'm trying to find evidence of another thing I swear I heard about where someone had some instructions from first principals how to read the data, but all the way from something like understanding the language to data format. I listened to something in a tech podcast but can't find it.

Depends on when the next intelligent species arises. Maybe they were the one that drove us to extinction!

But even if it takes a few million years, we've build massive amounts of infrastructure that won't be going away anytime soon.