Trying to make this not inflict self damage but having trouble, advise?

I'm experimenting with some ROBLOX-Made gear, trying to see how different attributes, like force acting on an arrow, can be modified through simple NumValues. Had some problems in other areas though the I figure would be good to understand if anyone can help

local Tool = script.Parent
local Remote = Tool:WaitForChild("Remote")
local Handle = Tool:WaitForChild("Handle")

local FriendlyFire = false

local AttackDamage = 35
local AttackAble = true
local AttackRestTime = 1

local ProjectileSpeed = 50

local MousePoint = Vector3.new()

local Arrows = {}

--returns the wielding player of this tool
function getPlayer()
	local char = Tool.Parent
	return game:GetService("Players"):GetPlayerFromCharacter(char)
end

--helpfully checks a table for a specific value
function contains(t, v)
	for _, val in pairs(t) do
		if val == v then
			return true
		end
	end
	return false
end

--tags a human for the ROBLOX KO system
function tagHuman(human)
	local tag = Instance.new("ObjectValue")
	tag.Value = getPlayer()
	tag.Name = "creator"
	tag.Parent = human
	game:GetService("Debris"):AddItem(tag)
end

**--used by checkTeams
function sameTeam(otherHuman)
	local player = getPlayer()
	local otherPlayer = game:GetService("Players"):GetPlayerFromCharacter(otherHuman.Parent)
	if player and otherPlayer then
		if player == otherPlayer then
			return true
		end
		if otherPlayer.Neutral then
			return false
		end
		return player.TeamColor == otherPlayer.TeamColor
	end
	return false
end

--use this to determine if you want this human to be harmed or not, returns boolean
function checkTeams(otherHuman)
	return not (sameTeam(otherHuman) and not FriendlyFire)
end**

function getArrow()
	local arrow = Instance.new("Part")
	arrow.FormFactor = "Custom"
	arrow.Size = Vector3.new(0.2, 0.4, 3)
	arrow.TopSurface = "Smooth"
	arrow.BottomSurface = "Smooth"
	arrow.CanCollide = false
	
	local mesh = Instance.new("SpecialMesh")
	mesh.MeshType = "FileMesh"
	mesh.MeshId = "rbxassetid://223379254"
	mesh.TextureId = "rbxassetid://2740083062"
	mesh.Scale = Vector3.new(0.6, 0.6, 0.6)
	mesh.Parent = arrow
	
	local lift = Instance.new("BodyForce")
	lift.force = Vector3.new(0, 196.2, 0) * arrow:GetMass() * 0.9
	lift.Parent = arrow
	
	local hit = Handle.Hit:Clone()
	hit.Parent = arrow
	hit.TimePosition = 0.2
	
	local projectile = Tool.Projectile:Clone()
	projectile.Disabled = false
	projectile.Parent = arrow
	
	return arrow
end

function onLeftDown()
	if not AttackAble then return end
	
	AttackAble = false
	delay(AttackRestTime, function()
		AttackAble = true
	end)
	
	Remote:FireClient(getPlayer(), "PlayAnimation", "BowFire")
	
	wait(0.3)
	
	Handle.Shot.Pitch = math.random(90,110)/100
	Handle.Shot:Play()
	
	local arrow = getArrow()
	arrow.CFrame = CFrame.new(Handle.Position, MousePoint)
	arrow.Velocity = arrow.CFrame.lookVector * ProjectileSpeed
	
	local c
	c = arrow.Touched:connect(function(part)
		if part:IsDescendantOf(Tool.Parent) then return end
		if contains(Arrows, part) then return end
		
		c:disconnect()
		arrow.Projectile:Destroy()
		
		local w = Instance.new("Weld")
		w.Part0 = part
		w.Part1 = arrow
		w.C0 = part.CFrame:toObjectSpace(arrow.CFrame)
		w.Parent = w.Part0
		
		arrow.Hit:Play()
		
**		if part.Parent and part.Parent:FindFirstChild("Humanoid") then
			local human = part.Parent.Humanoid
			if checkTeams(human) then
				tagHuman(human)
				human:TakeDamage(AttackDamage)
			end
		end
	end)	**
	
	table.insert(Arrows, arrow)
	arrow.Parent = workspace
	game:GetService("Debris"):AddItem(arrow, 10)
end

function onMouseUpdate(targetPoint)
	MousePoint = targetPoint
end

function onRemote(player, func, ...)
	if player ~= getPlayer() then return end
	
	if func == "LeftDown" then
		onLeftDown(...)
	elseif func == "UpdateMouse" then
		onMouseUpdate(...)
	end
end

Remote.OnServerEvent:connect(onRemote)

I bolded the main areas I'm focusing on. I've tried a few things, none of which are working, and a lot of this is possibly due to my difficulty understanding the first block of bolded code. It seems as though this provides a series of either true or false, but how does the code aggrigate these responses in the next part under checkteams()? It needs to be true to fire the later bolded code, but I'm just a bit confused as to how it got here. Thank you!

edit: Ahh bolding doesn't work here, lemme get the line numbers

ok, 42 - 61, and 128 - 135