Who was the first person to enter Heaven?

This question can be answered in a number of ways.  First, God created Heaven (Genesis 1:1) and therefore He would technically be the first one there.  Second, Jesus Christ entered Heaven after His resurrection and offered His blood on the mercy seat to provide salvation to mankind (Hebrews 6:20; 9:12).  It is through Jesus Christ that those who have put their faith in God through any dispensation can enter Heaven.  As to being the first person of mankind (not counting Christ) we do not know.  Everyone who put their faith in God before the cross went to Abraham’s bosom (Luke 16:22) and were not allowed into Heaven until Jesus died for their sins.  Only God knows who was the first to enter the pearly gates, but it really doesn’t matter all that much.  The thing that does matter is that a way has been provided so we can be there.