Where in the Bible did the authority to make new church practices come from?

So what's confused me for the longest time is the rules regarding holy days of obligation, Easter, and a big focus on holy Communion and mass attendance. To me it feels like there are a lot of things that Jesus didn't actually talk about and were brought about later, like palm Sunday, and I'm worried that the celebration of things that happened is blocking the real message of Jesus in treating others the right way and spreading God's word through our words and actions. Also putting this out there, I feel like the church doesn't really teach on moderation anymore and on how life without things can be more fulfilling. We get a short trial of this in lent but other than that it's the regular old testament which makes sense from a moral perspective. What changed?

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u/Inevitable_Cap630 — 5 days ago