Is all non-human traffic click fraud?

No. Plenty of non-human traffic is ordinary infrastructure: search crawlers, uptime monitors, SEO tools and link checkers. They declare themselves and cause no harm. Fraud is the subset built to look human and extract money, whether that is a competitor draining your budget or a script manufacturing clicks for a payout. Automated does not mean malicious, and treating every bot as an enemy causes its own damage.