Jacobean period was when James I was in power.
Elizabethan period was when Elizabeth was in power.
Now the Revenger's Tragedy can be argued as black comedy. It's farcical and ridiculous and I'm starting to see the humour within the play. You can argue that it isn't a revege tragedy but a comedy.
So when you look at it through this viewpoint, maybe it'll help you understand the play.
Also the book "Succes in HSC Extension Revenge Tragedy by Pattinsons" have a good plot summary. I'm sure you could borrow it in a library, the book will help you understand the play a bit better.