The concept of meaning originates in the subjective not the objective, wherefore absolute meaning does not exist.
There is a difference between meaning and purpose. Meaning is something we give - it is not objective, it is subjective. Purpose can be defined mathematically - for example, the purpose of an electron is to spin around an atom at X speed with X other mathematical equation.
To understand your purpose, you would need to understand the mathematical equation behind all things, which is impossible.
The argument against “the ant (or whatever else) is optimizing for something (such as survival)” is that there are too many criteria that need to be taken into account, including millions of firing neurons and different needs that we’re not aware of.
So, is there value in explaining something such as saying "that person is optimizing of X in life"?
I'd say yes, as long as we remember that stories are an aproimation for finding out our drives.
It’s not about whether the story is true. It’s whether you realize that it’s the story that drives you. So why go against these approximations? There is value in these, such as being able to better predict human functioning.
Conclusion: the story of objectivity ultimately remains a story as it lies in our subjective perception. There is nothing we can be certain of, we can only be self-aware of the stories we tell ourselves.