Reed's elasticity seems more like an influence from Plastic Man than an archetype of water. The Human Torch seems more influenced by the android Human Torch who partnered sometimes with the original Submariner. There had been an Invisible Girl in the movies. The only original I think was the Thing, but he didn't look like rock at first.
Also, the whole issue is complicated by the clear alignment of personality traits with powers in the case of Susan and Johnny. Then there's possibly a kind of irony in the misalignment in the others. Reed's seeming weakness as an intellectual=fantastic ability to metamorphose? While Ben's seeming strength=something more monstrous?