I built a WordPress ad management plugin for a client sometimes back and I believe it may be useful to other especially bloggers, content creators, and website owners who want to monetize their site. It's called Smartspot Ad Manager. Upload a banner, set the link, pick the pages, post, and section it shows on. (Works with any permalink structure of choice) That's mostly it. Compatible with most(all) page builders. Download: https://wordpress.org/plugins/smartspot-ad-manager/

It's open and you can contribute : https://github.com/isaacshed/smartspot-ad-manager/