First off lets just think about whether or not Loki was trying to fight the human. Remember he's trying to talk to the other Loki properly. Perhaps the Variant was testing Loki to see if he wanted an all out fight or actually wanted to talk. The both of them are testing each other and trying to get the measure of one another. Loki clearly wants to talk to the Variant so best not to start all out warfare here.
However, discounting that the human was being possessed by the Variant. It seems most likely that under the possession the Variant was also giving powers to the human to increase their strength: they did throw Loki an awfully long way after all. Remember that we saw Agnes do something similar in WandaVision
where she possessed Ralph and gave him superspeed.
I think we also see this from Dormammu in Doctor Strange. It's possible the Variant is just doing that; it's just a Loki power we haven't been shown. However, we do see it shown in the comics. For something somewhat similar we see Loki increase Sandu's extra sensory abilities a thousand times in the comics, see Journey into Mystery Vol. 1 Issue 91:
Click image to enlarge.