So, i hate that i've never thought of using this even though i play druid 4 times out of 5 for about 5 years, but i don't think that this would work in 5e if you're following the book. People aren't open containers in most cases
One of those things the DM is there for, I suppose. The rules as they're set up are there to help facilitate things, but shouldn't be overly relied on sometimes, either. So, the DM would decide something like whether using the spell that way could work or not, and then how they might have to adjust the difficulty of the roll(s) required to use it that way. Maybe consider it a touch attack version of the spell and include a DC for whether it would work if you even land the touch attack? Give the player a chance to do it, but no guarantee that it will work just because you can argue that a human is a container and the ordinary spell never required much else than that aspect.
i remember when I had used area of frost but only had lv0 slots left to use so i wide-cast create water intending to form ice on the ground to trip up the mobs, but my DM fluffed it up to manifesting just above the aoe so the water formed ice needles dealing 4d4 piercing dmg. good times, good times.