If you're an avid open-source user who would love to help advance a project, there's a lot you can contribute whether you can program or not:
Provide constructive feedback, file bug reports, improve the documentation or help out maintaining the web & social media presence. Spread the word and recommend the projects you love to others (btw, I run Arch 😂)
Say "thank you" and tell developers to "keep up the great work". That form of contribution means a lot more than you could possibly imagine.