It's up to you if it helps you to think of it that way. However, if everyone is on the spectrum, then "autism" is less useful as a term for categorizing a group of people with a shared condition that may need help/accommodation in specific ways. How do you provide special services for autistic people when everyone is "on the spectrum". There's a solution, but requires a different way of categorizing people.

"spectrum" is a useful analogy to the EM spectrum, which is a literal spectrum. The autism spectrum is not a literal spectrum, we call it that because it's a useful way to understand neurodiveristy. However, like any analogy, it eventually falls apart as you go deeper into applying it. It's not the complete way to understand autism nor is it the only applicable analogy.

Autism is not fully understood, but it is characterized by several dimensions that each involve variation from the norm due to a complex of causes. This is why the "spectrum" analogy falls apart--it reduced autism to one dimension. Another analogy might be a crystal that grows in multiple directions, with more growth from the centre being divergence from the norm. Some crystals grow a little bit in all directions, some grow only in a couple directions, and every other combination of amount x direction.