Energy is not really manmade. It's not a physical object, but that doesn't mean that we invented it. It's a pattern of behavior that we gave a name to. Whether we notice the pattern or not, the pattern is still there.

It's the same as gravity - it's not a physical object, it's a pattern that describes how massive objects interact. But you wouldn't argue that gravity doesn't exist, would you?

You can say that about all of math and science. It’s all language to describe observations of the universe.

What else are you going to do?

Small aside: From this perspective 'conservatipn of energy' is a redundant statement. Of course energy must be conserved or else the equations are wrong. The definition of energy is it's conservation.

That’s circular reasoning on your part. “The definition of energy is its conservation” is false so that’s not redundant. Don’t know where you got that from.

The curious thing about matter is that if you zoom in far enough, you'll find that it is energy, and energy is basically vibrations and waves rippling.

The way it's often described, if you zoom into a hydrogen atom, it's mostly empty space, let's say the proton is the size of a tennis ball, the electron is like a grain of sand a kilometer away.

But then zoom further in, inside the proton, and it's made of three quarks. But those three quarks make up only 1% of the proton's total mass! The other 99% is like a boiling and roiling little sea of all sorts of particles popping in and out of existence, such as gluons (which keep those three quarks bound tightly together), as well as more quarks, and other more exotic particles, some of them heavier than the proton itself! But they disappear almost at the same instant in which they are created. This is a constant, non-stop process, happening inside every proton and neutron in the universe.

And what do you call that virtual stuff that always keeps on popping in and out of existence between the three permanent (aka valance) quarks and makes up 99% of the proton's mass? That's energy.

Now zoom back out, and back in, towards the electron; what's going on there? It's a lone particle (also a wave, but let's not get into that now), there is no 1% / 99% of something, all valance no virtual.
But nudge that particle towards its' antimatter counterpart, the positron, and both particles dissolve into a flurry of photons that instantly fly away at the speed of light - pure energy. It's as if their little charge shells (electron - negative, positron - positive) dissolve and a flash of pure energy comes out.
This also applies to quarks and their antiquark counterparts.

That right there, is Einstein's E=mc^2 in action, in all its' glory. Energy equals mass.

Energy is something. It is there, even at the most fundamental and abstract level. It can be measured precisely, and explains so much so clearly, it's incredible.

EDIT: fixed a sentence in the wrong place

If it can predict what will happen it is real

It's as made up as time, but it's as real as anything can be understood to be, with emphasis on 'understood'. It doesn't exist in actuality mostly because our words and models don't describe it even close to well enough to consider the actual thing. It's like a really poor translation of a word, it might get us closer to understanding what's going on but will never be if your goal is to describe it to something like the human mind.

I'm no expert, but I was an aerospace engineering student once upon a time. So here's my take:

Energy is not "manmade" because it would still exist and be transferred between systems even if humans didn't exist.

Stars would still burn. Gravity would still pull. Inertia would still inert. Accelerating mass would still require energy. There just wouldn't be anyone around to punch in numbers into a calculator and name the concept "energy".

Of course all math and physics are "manmade" insofar as they are theorized, discovered, and proven by humans. But these phenomena would still exist regardless of humanity. This feels analogous to asking if "electricity" is manmade. We discovered and named the physical concept; it doesn't mean we invented it. If a tree falls in the forest and no one is around to hear it, it still makes a sound.

So, what would it be a medium of, then? I mean money is a medium of exchange. And by your logic, energy is a medium of ____ ???