Firstly, I would just like to refute 'If all knowledge is based on faith, then is science reliable?' because I've seen it been made before to argue [random-bullshit-thing] is worth considering. Science isn't based on knowledge, it's based on experimental results, models, and extrapolation. Actual faith is not based on that.

There's a really good argument to be made that our senses are not telling us the truth, they just tell us what is beneficial to survive and reproduce. However, this is not the case for instruments that measure, say, gravitational waves.

There is a real reality out there, and it's unlikely we can perceive it. Perhaps the universe happened all at once, but our brain processing happens in consecutive slices of reality, so we perceive time.

Personally, my (pessimistic) gut feeling is that we don't exist. How could anything? It's that Prime Mover argument. Because the Big Bang, because multiverse bubbles colliding...

I think the universe might not actually exist, nothing does. But the potential possibilities make it exist relative to the baseline of nothing. Just like when you climb Everest, your total altitude change is 0 because coming down cancels out going up. The universe is just a potential that is cancelled out by something else, so existence remains at 0 in total.