The first people to recognise that Lord Jesus Christ is a being of similar eternal characteristics as the real God and to hold to His teachings with hope of those teachings making them righteous did it seems put an emphasis on keeping His crucifixion and subsequent resurrection well remembered as part of staying true to it. This is perhaps due to the importance of these most outstanding events as part of the testimony of the being who is the God and Father to Him in that by raising Jesus, God the Father was testifying to all these disciples and to some extent to all humanity that Jesus is His beloved precious and pleasing Son from aeons past and for aeons to come. The first disciples were mainly Jewish and already kept Saturday as rest day for God but they made Sunday a day of remebrance of Jesus' resurrection too by making it a day to rejoice in The Lord, Lord Jesus the Christ.
