I chose Bitcoin as a research subject for a project I'm working on. I have been doing some research on the topic but have to say that I'm even more confused now than yesterday. I'd appreciate if anyone here can give a human answer to the following questions in a way that an unexperienced person can understand. If you want to help me then please bear in mind that I'm completely new to all of this so if my questions make no sense I apologise in advance. I still don't get the following, please help me with the following questions about Bitcoin:

1) What does it mean that bitcoin is a public ledger? For example I have read that every transaction is recorded on the ledger, how can a person then own 1 bitcoin if bitcoin is the ledger? 2) When someone says that they own 1 bitcoin, what do they really own? Is it one Bitcoin block? 3) What is a hash? 4) What does it mean that bitcoin is a decentralised digital currency? This part I understand that bitcoin is virtual, but what does decentralised mean? For example when we consider that it is 1 public ledger, this ledger must exist somewhere to be able to record transactions, so then there must be a centre of control to update the ledger? 5) What does it mean to mine a bitcoin? I read that computers solve a puzzle and are rewarded with one bitcoin, how does this happen?

I'm sorry if I'm all over the place. I'd really appreciate your help because I cannot find any of this information online explained in a way that I understand. Thank you in advance for your time.