You need to discern the obvious difference between the God depicted in the Christian bible and the Gods portrayed in the many other religious faiths.
If anything the christian god seems more obviously and overtly man-made than the gods portrayed in some other religions, specifically because the christian god is achingly anthropomorphic - a kind of super-human, just the kind of god you'd expect humans to come up with. At least some other religions have gods that seem much more universally linked to existence, to broader nature etc. Surely the most obvious test of a god (particularly linking to whether it is likely to be man made) would be whether it would remain relevant if humans did not exist. Without humans the christian god is irrelevant, so inextricably linked to people (and not just all people, but a tiny group of people in a particular place at a particular time).
Imagine if dolphins evolved sufficiently to be able to create gods - they'd likely create a dolphin-like god that is a kind of super-dolphin, that interacts pretty well exclusively with dolphins and has no interest in, nor relevance to, land, rather than sea. We'd dismiss this god as obviously a dolphin-made god. The christian god demonstrate exactly these characteristics, except being man-made rather than dolphin-made.