Life is nothing

[Fake Messiah]

What's the point if we are just a bunch of cells and nothing else?

First of all we're not just cells, we are very special because, as a thinking and creative life-form, we are one of the most fortunate collections of atoms in all the universe. Look up at the night sky and feel that we are part of it, made of stars.

Also you think that atheism claims that we are all alone and we don't need anyone, should care about ourselves and nothing else; but did you made all your clothes, food you eat, your furniture, entertainment, computer or did you have other people make you some of those stuff? And as banal as it seems that's what we do to survive. You do what you can and other people do what they can. And also people are social animals. You do stuff because it's your duty (work) and other stuff (like laughing, being with friends, going to theater) because it gives you pleasure. Now, why altruism exists is bit complicated answer but it's there, nothing supernatural about it.

You could say biological meaning of human life is to procreate, but since we are intelligent we can overcome those reasons and enjoy in discovering nature, or humor etc.
For instance you have sharks that live like you describe: live by themselves. In fact they are so anti social that they have problems even with finding mating partner so that females sometimes even use parthenogenesis.

On the other hand I don't see that religion gives any meaning to life only to death.