This is a really deep and complex topic.

I think you're kind of asking the wrong question. "Why are we here?" well we will probably never know. I'd prefer to ask "Now that we're here, what are we going to do?". Life can have whatever meaning you apply to it. Some people want to squander it, enjoy it, or spend it seeking the truth or enlightenment. Maybe they're all correct. Maybe there is no correct answer.

There are some great theories out there. One is that we are all neurons making up part of a big biological super-computer (I wonder what we're trying to solve). Another is that we are living in a simulation. Have a read of Nick Bostroms trilemma if you really want your mind blown :-

https://en.wikipedia.org/wiki/Simulation_hypothesis