Jesus is simply stating what is going to happen next. He is finally going to the Father to finish the whole journey begun with his holy conception. He tells Mary that she should not worry or cling to him - hold him back from this final stage.
Do not cling to me, for I have not yet ascended to the Father
Mary had lost him once already under tragic and horrific circumstances, she didn’t want to lose him again!
This is nothing about making him unclean. He was always holy, and now he is risen and going to the Father, his holiness is now baked in.
Jesus also emphasises the benefits of going to the same God Mary had, his God. They were both worshiping the same God and His purposes for Jesus leaving, were going to be good for Mary too! IOW, 'let me go now Mary for this next part is very important'.
By his death, Jesus opened a new and life-giving way through the curtain into the Most Holy Place Heb 10:20
Jesus death had finished the process or salvation. His new life and exaltation was his reward for doing a great job. He would present himself to God as the wavesheaf offering picturing the new harvest. Jesus being the first fruit, the firstborn from the dead. Col 1:18
He shall wave the sheaf before the Lord, to be accepted on your behalf; on the day after the Sabbath the priest shall wave it Lev 23
Notice the alignment of the time - Jesus rose late Saturday, this is now Sunday, the day after the Sabbath.
Certainly there are other accounts of an ascension, but there are clearly more than one 'going to the Father', and need not be construed as a contradiction or error of the text. The plan for Jesus is totally laid out by the Father and/through the type of every OT prophecy that points to what Jesus needed to accomplish, how and certainly when - God doesn't need to be late for anything! Certainly not this!
The wavesheaf offering practiced for centuries was only a 'shadow' - now that the REAL THING, Jesus, is here and ready, he must go.
Him finalising the Death - burial - rising sequence is this initial 'going to the Father'. He has a reward and exaltation to receive to go with his new eternal life.