Maybe your leader is bad at leading, then. Remember every store is different. We have multiple team members at 15+ years who are SLOWWWW but do their best to change and follow new guidelines and guess what...they're not going anywhere, not being forced out, not being outed.
I've worked, supported, or trained at 6 different stores in the past year. At none of them I saw this age discrimination that is being thrown about. I did see, however, younger people (from high school to college) deciding that hiding in a corner and going on their phone is OK, telling the leader that is coaching them "I don't care, keep coaching me, I'm not going to do what you're asking" is the right way to respond to a conversation that is meant to help them, and not understand simple requests like "follow up with your leader before you leave" or "know sales from yesterday in your department". It's easy, even for high school kids.
There may be something illegal happening in your store, but in my own (long time) experience, I don't see anything that is telling Target leaders to age discriminate.
Have you seen all of the training material available to team members now? Have you been a part of the training that was seemingly mandatory when we decided to move toward modernization? It was all very in depth and fun, and I would consider it the "team effort" you're looking for to embrace change.
I'm going to close my rant off with saying that I'm not discrediting anything of your own experience, it may be like that where you're located. I'm just offering another diverse perspective that just shows that there are good stores, districts, or groups even, where I can't find anything to support your claims.