Not everyone has a perfect credit score. The result of a less than perfect score is a high interest rate loan. A bad credit score tells the lender that the risk is higher and therefore loans for high risk people have higher interest rates. The higher rate acts as an insurance policy for the lender.
Your credit score is based on your current circumstances and your credit history. Loans for people with bad credit history are harder to arrange because the lender has to be sure the money will be repaid. This often results in a higher loan interest rate. Credit history is important, but black marks on your records to fade over time as you demonstrate trust to the lender.