Am I too old to learn something new at 50?

The learning was never the issue. You have learned harder things than this under worse conditions, usually while someone was depending on you.

What you are really asking is whether you will be allowed to be a beginner in public at an age where people expect you to be finished. The answer is that nobody is watching as closely as you think, and the ones who are will lose interest within a month.

Start with one thing you can do badly this week. Competence follows repetition, and repetition follows starting.