Economically speaking, (bank) loans and bonds are almost the same thing.
There's a bit of a legal difference. And bonds are expected to be traded relatively easily, but your creditor selling your loan to someone else is not quite as common.
A re-insurer is someone who insures insurance companies. Many insurance contracts for you as an individual have you pay for the first few (thousand..) dollars of damage, and the insurance companies covers everything afterwards.
Of that liability, insurance companies cover the first few (million) dollars of damage, and often pass on the excess liability afterwards to yet another specialised company. The re-insurer.
Catastrophe bonds are a way for bond investors to take the liability that would normally go to re-insurers. Of course, in return for taking on some liability, they get paid. Just like you pay your insurance company a premium.
Cat bonds are fascinating. What you describe is one of many structures. In essence, bank loans are to bond markets as reinsurers are to cat bonds.