How can I change my Monsters AI?

Well Im remaking the known game BLOXore and Im changing the monsters up I need to figure out to change there ai so the player cant just stand and do dmg,Becuase I want the AI to allow the monster to jump over the player and attack from behind and such,Thats all thanks for reading this!

local larm = script.Parent:FindFirstChild("Left Arm")
local rarm = script.Parent:FindFirstChild("Right Arm")

function findNearestTorso(pos)
	local list = game.Workspace:children()
	local torso = nil
	local dist = 15
	local temp = nil
	local human = nil
	local temp2 = nil
	for x = 1, #list do
		temp2 = list[x]
		if (temp2.className == "Model") and (temp2 ~= script.Parent) and game.Players:GetPlayerFromCharacter(temp2)~=nil then
			temp = temp2:findFirstChild("Right Arm")
			human = temp2:findFirstChild("Humanoid")
			if (temp ~= nil) and (human ~= nil) and (human.Health > 0) then
				if (temp.Position - pos).magnitude < dist then
					torso = temp
					dist = (temp.Position - pos).magnitude
				end
			end
		end
	end
	return torso
end




while true do
	wait()
	local target = findNearestTorso(script.Parent.Torso.Position)
	if target ~= nil then
		script.Parent.Humanoid:MoveTo(target.Position, target)
	end

end

Thats the script I belive is the problem