It’s not more heretical to claim that jesus wasn’t entirely human, quite the opposite in fact. It’s a very old theological debate of homoousianism vs heteroousianism vs homoiousianism (same substance, different substance, similar substance). This debate was settled in the 4th century and Arianism (heteroousianism) was rejected

Homoousianism - god the father is of the same substance as Christ, is the most prevalent vision nowadays, which means that christ is purely divine and not human