Ok. You are an "at will
" employee, so legally you can be terminated at any time with or without cause. So, you have no wrongful termination
Now, only you can decide this. If you're not sure, then you probably have no real evidence to support the position that either your age or your gender were the basis for your termination. If you had heard some comments concerning either, you would have mentioned them most likely.
Regardless, you would be giving up their severance in return for the chance to file a claim of age or gender discrimination
against them. Nothing about the fact that they offered this to you suggest, in any way, that they actually are discriminating and want to buiy you out. It is common in the present age to offer severance and ask for a release of claims. My point is that, on the facts you've given me, I see no reason for you to not take the severance. If you, who worked there and felt the day to day atmosphere, are unsure if you might have been discriminated against, what evidence would you present to a jury to convince them of that fact?
Now, I'm not saying that you have no potential for a claim. I don't know everything that you know about this place and the working environment. I only know the facts you've presented. The fact that most of the people in the corporation are young isn't a fact that is useful. Courts don't accept statistical arguments anymore. You have to demonstrate, in your instance, that you were specifically selected for lay off based on your age or gender. The employer can argue that you were selected as one with the least tenure, or whatever other argument they might make.
Again, only you can decide if you feel like you have a claim worth giving up severance to pursue.