Do I need blockchain knowledge to follow this documentation?
Your blockchain knowledge will be useful but if you are reading this that means you are on the right track.
I'm a Polkadot builder, do I need this?
If you are already a builder on Polkadot/Kusama ecosystem you can most likely skip Introduction chapter. But it is recommended that you read about available Networks.
Do I need to be a developer to understand Introduction chapter?
To use this introduction chapter you do not need any programming skills, and it will be useful later when you step into more advanced topics.