Yes, but the continuum is presumed to be one-dimensional. Most definitions include that. E.g., Merriam-Webster: a continuous sequence or range

Sequences are one-dimensional.

You can use the word to refer to other things, but it's misleading by analogy to an optical spectrum, and probably misleading by definition, too.

It's just a poor choice of language when you're trying to communicate broadly with people, especially those who have a vested interest in not understanding you.

Again, you don't generally talk about the "spectrum of literature" unless you're forcing it to be one-dimensional (e.g. refined prose for the sophisticated down through crude trash for the masses).

When you talk about the "political spectrum" you mean left/right. You don't mean weird things like leftist libertarians.

So I agree that there are continuums, but there area lot of them. For instance, mutations in the AMH gene cause atypical development of female sex organs in chromosomally male individuals. So this is a continuum of (no female sex organs -> female sex organs) which can occur (not frequently) independent of other genotypes and phenotypes.

Calling this multivaried mess a "spectrum" does not do it justice, as I said.