Yeah, you are absolutely onto something here. The debate about what is a species and what is not is really heated, and it's changing all the time. Most modern species are determined more by genetics than the class "whom can have children with whom" definition that used to be common back in the days.
What I believe is that we will never get a clear definition of what a species is. In nature, everything is as you say a continuum, and we humans want to categorize everything, which is impossible to do with nature. Really, what we're trying to do is to categorize all life on earth, so of course it will be next to impossible to make it nice and easy.
Thanks for leaving a great comment, @zool237! I'm sorry I didn't get to reply to your earlier.
Best regards from @valth