Ah yes, the distinction between dogma and discipline is lost. . .and what you have also failed to grasp is that the eating of meat was never a sin.
If eating meat were a sin, it would be forbidden at all times.
But it is a discipline (and just about everybody who is not a complete and utter couch potato has disciplined his or her body through ‘giving up’ something, whether sweets, fats, carbs, sodas. . .or by ‘giving up’ just sitting around in order to exercise).
Disciplines help our bodies (and minds) to function well.
They are changeable because different people have different needs at different times.
The sacrament (it is a sacrament, instituted by God Himself, not a discipline administered, under God’s guidance and not in defiance of His will, by men striving to follow out His commands) of Holy Orders is something completely different. It isn’t a 'job made by men to do X, Y, and Z, but a calling from God Himself, and involving the methodology HE (not ‘people’) has chosen, which is why HE has the authority to decide what HE will use in a sacrament, and WE do not.
So if you’re going to address ‘what the Church has changed’ why don’t you tell me what SACRAMENTS it has changed. When did the Church decide to change ‘bread and wine’ for the Eucharist into cookies and milk --oh wait, it didn’t. When did the Church decide to let men marry men and women marry women–oh wait, it didn’t. When did the sacrament of reconciliation change to allow people to ‘phone in confession’ or have ‘auto-forgiveness’ --oh wait, it didn’t. When did baptism change from a trinitarian formula with water to a champagne bath in the name of Mother Earth --oh wait, it didn’t.
Sure, ‘external’ changes happened. Reconciliation went from public to private, but at any time could become public again (just as ordination went from married and single men to single only, but could become married and single again), the Eucharist age for 1st communion has been anything from birth upward in the Eastern churches to ages 7, 12, 14. . .
Those are EXTERNALS.
The rite of ordination does not use exactly the same words or garments or ‘underground catacombs’ but the purpose is the same.
If you’re really interested in the history of the Church and its sacraments, then instead of pulling out the usual, "But if the Church did X as a change, then obviously ANYTHING can change’ claptrap you would have the intellectual honesty and courtesy to know what the Church teaches and why so that if you still didn’t agree, at least you wouldn’t look like a fool trying to make a comparison that has absolutely nothing to do with the facts (generic ‘you’ of course).