Could these simulated cells.. Evolve?

What you're thinking of is a 'genetic algorithm'

https://np.reddit.com/r/Art/comments/454joy/drawing_experiment_every_line_goes_through_the/czvd1rf

^ That explanation is pretty thorough, but remember evolution is basically just the phenomenon of having an environment with some conditions - - these conditions exert some kind of influence on whatever objects are in that environment. If these objects can pass on what they're like (with some changes that originate from somewhere, even the environment or other objects) and succeed or fail in that propagation based on how well fit they are to the influences of the environment, then you will basically see an optimization over time of objects to environment.

A 'genetic' algorithm is humans mimicking the step wise process that leads evolution by saying:

"Here's a mathematically expressed set of conditions, here's a population with some distribution of traits that succeed and fail within those conditions, here's how members pair up to transmit their traits to the next generation, run this a bunch of times"

Could you create a natural AI

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

AIs already exist!

by.. Giving birth to it?

With a generous interpretation of the word "birth", this has already been done.

But you're talking about something that's orders of magnitude more difficult.

You're talking about computationally simulating every last degree of freedom for the dynamical system of a cell - - look at the resources required to simulate just a molecule of hydrogen.