God invented spiders because He loves us. They perform a useful function in keeping down the insect population. Imagine a world overrun with flies and other insects!

Now had you asked why did God invent mosquitoes...?🤔

Pollinators be pollinating you gotta make sure that everything is planted in the right time. Everyone has to deal with their own garden not everybody can get to the root, and even if they could not everyone likes to travel so we have spiders. Just make sure you have the proper salve when you need it.