I’m not trying to push an agenda. I don’t know what you mean by “picking and choosing writings”. I’m still not sure exactly what you’re saying.
If you’re saying there are no such thing as “founding fathers”, I think that’s just wrong in the sense that the myth of the founding fathers is a part of American culture and is taught in American schools. There is no “founding father” gene or element, but that doesn’t mean they don’t exist.
If you’re saying all the people who were delegates at those conventions are equally “founding fathers” because they helped forge the documents, then sure, I can respect that opinion. But some of those delegates undoubtedly played a significantly larger role in early American history than others (including the creation of those documents!). Hence why we learn about a select few of them, and not all ~100 (although I guess that would also be impractical in a school setting). The specific number 7 is a bit arbitrary, but ~10 were a lot more important than the rest.