No doubt they were shadows of what is to come and memorial of what has come. But Paul didn't understand that they were done away with.
Col 2:16 Let no man therefore judge you in meat, or in drink, or in respect of an holyday, or of the new moon, or of the sabbath days:
Col 2:17 Which are a shadow of things to come; but the body is of Christ.
They ARE a shadow of things to come. Paul was writing how many years after Christ death here? Thirty or so? Thirty or so years have gone by and Paul thinks the holy days and sabbaths ARE, not were shadows of things to come.
But what's really interesting is if you take out the words, punctuation and numbered verses that translators add to the greek to make it more "clear":
Then do not let anyone judge you in eating or in drinking or in part of a feast, or of a new moon or of sabbaths, which are a shadow of coming things, but the body of Christ.
What does it say? Kind of changes the whole meaning when read as it was originally. It seems to be saying that you shouldn't let anyone judge your for how you observe God's Holy Days except for the body of Christ. Your brethren. And the greek here isn't referring to any other days except the ones God designated as holy.
Believe it or not.