I'm developing my first children's website in python. I would like to know if it is mandatory for a website to have copyright?
Nope. It isn’t.
Copyright is an inherent right. Any artwork, content or creative work which is original in nature, has inherent copyright vested in the work - which means, the copyright exists in every work which is originally created.
Filing a Copyright application, however, gives you the advantage of having an application or claim ownership, date using which you can claim your rights , etc