When Vicente approached the group of people looking for his head, he immediately made those beasts believe this was his group.
Beasts didn't understand human language any more than humans understood them.
When they sensed that this human had killed three of their own and saw these other humans in the area, they immediately assumed that all humans were allies.
Their main target at the beginning of the confrontation was Vice since he was the one who had killed the three monkeys. However, half of the beasts that had appeared on the area's outskirts were already attacking the rest of the group that Nova had summoned there.
Vicente felt a level 5 Acolyte, a large monkey similar to the one he had killed, coming towards him and quickly floated away with his metals, heading towards the leader of Defiant Tyranny.