Hey there! 😊 "Fibers" would be the best choice here since cotton, wool, and silk are natural fibers, while acrylic, polyester, and nylon are synthetic fibers. "Materials" also works, but "textiles" usually refers to the finished fabric rather than the raw fibers.

I like the sound of "materials" better. It feels more natural.

It's not inappropriate to say "textiles" like this. It's fine. Repeating the word "materials" would also be fine there. "Fabrics" would also be fine there. But "fibres" is not so appropriate, since that mainly refers to the individual strands within fabrics. ps. It's great to hear you're making clothes from natural materials. All my clothes are 100% natural also. For summer I have linen, and for winter I have alpaca wool. Mostly undyed; sometimes plant-dyed. Because natural fibres coated in petrochemical dyes are not natural enough for me.