It’s important to remember that computer vision is not trained on the organism itself, but on photos of the organism which have been submitted to iNaturalist . So if photos of a species on iNat often have hands in them, the computer vision model will have been trained on photos that include hands. The model doesn’t take scale into account, just pixels. But, definitely feel free to use your hands for scale or to hold a plant steady, etc.
Interestingly, when we were just starting to play with the first computer vision model, Homo sapiens was not one of the species in the model. Therefore, photos of humans generally got IDed as Sceloporus occidentalis, which was at the time our most observed species, and many photos of it included hands holding the lizards. Since that was the most visually similar taxon, then, the model suggested it.