Since school ended, I have been very bored. Until I started thinking; what if all of the themes in the Lego Universe are connected?
DISCLAIMER: This theory only includes the Original Lego IPs, and no Licensed Themes. As such, this theory disregards the Multiverse idea proposed in The Lego Movie and Lego Dimensions. Also, if you believe I missed a specific theme (please don't add subthemes, as those are covered under the main theme) then do not hesitate to tell me. So, read on!
Here is my theory. (If it shows you can edit it, please don't.)
EDIT: Okay, sorry for the inconvenience, but hopefully it will work now.