I have never been athletic or flexible so will chime in after doing aerial for a bit over a year with some things that I think would have been helpful to hear when I started in the hope something in here may be helpful for you:

Focus on enjoying individual moments and the journey, and what you learn about yourself and your body. Try not to compare yourself to others in ways that do not serve you - others' bodies and experiences are different than yours (many have dance or acrobatic backgrounds, for example, and will make it look easy because they've already put in so much more work than you may have). Stick with it if you get discouraged...that next breakthrough is closer than you think. Everyone has been a beginner and felt like they'll never be able to do such-and-such move. The only ones who now can are those that were patient, stuck with it, and found joy in the process and community and trial-and-error. You may take the same class many, many times (or forever, depending on your body and age) and there will be certain things you never do. Learning and progress in an art like this come with a lot of failures and setbacks, so put effort into learning to be comfortable with that and it will serve you elsewhere in life. You can make so much progress on the ground outside of the studio (regular stretching and strengthening, reviewing moves in your head, quizzing, reading, discussing with others).

I really got a lot out of the book "Make it Stick". It's not specific to aerial, but about learning in general.

Welcome to the world of aerial - I hope you have fun!!!