It's not a fallacy if the thing your projecting onto is an actual human with an actual human mind. Another way to see this is as using the priors on how humans tend to behave that evolution has provided you.

That only works if you're (a) not running in to cultural differences and (b) not dealing with someone who has major neurological differences. Using your default priors on "how humans work" to handle an autistic or a schizophrenic is probably going to produce sub-par results. Same if you assume that "homosexuality is wrong" or "steak is delicious" is culturally universal.

It's unlikely that you'll run in to someone who prioritizes prime-sized stacks of pebbles, but it's entirely likely you'll run in to people who thinks eating meat is wrong, or that gay marriage ought to be legalized :)