That's because of the risk associated with PayPal's terms of service; seller protection does not cover cryptocurrency.  PayPal is a notorious way for scammers to get free bitcoin.  They buy the bitcoin, dispute the charges, and are refunded the money which is deducted from the seller's account.  Since Bitcoin is irreversible the seller is left without recourse, and PayPal has zero incentive to assist.

You being a newbie with no trade history you are unlikely to find someone willing to take the risk.