It's fundamentally your leader's charge to create an environment where you can produce high quality work and sustain. Part of that sustenance is you feeling like you can learn, grow, and with that growth deliver increasing value. Based on at least your side of the description, I think what you have is a failing manager who's 1) eschewing proper delegation and 2) a peer who isn't collaborating well. These two things will lead to shitty outcomes for the business. You'll either have crappy productivity (either through wasted time or low quality), or you'll have a work culture that breeds turnover, possibly both.
You should have an honest conversation with your leader about your commitment to being part of a productive team and voice your concern about how the team dynamic is affecting you. This should be something you lay out honestly in a 1:1 setting.
If your leader is worth staying with and working for, they'll take you seriously and try to help.
If they balk, offer excuses, or do anything short of hearing you out and giving a thoughtful, rational response, get on the market. You have a skillset that is in demand, you'll likely be able to try and find something that's a better fit.