Thank you for writing. Yes, customs in the Catholic Church can and do change over time, you are correct. And it is important to note and understand the differences between such customs (disciplines) and defined truths of the faith (doctrine).
Whereas something such as celibacy for priests is a disciple and subject to change, the male only priesthood falls into the category of doctrine and so cannot. This was stated definitively by Pope St. John Paul II in his 1994 Apostolic Letter Ordinatio Sacerdotalis.
After expounding upon the matter for several paragraphs, the Holy Father concludes:
Wherefore, in order that all doubt may be removed regarding a matter of great importance, a matter which pertains to the Church’s divine constitution itself, in virtue of my ministry of confirming the brethren (cf. Lk 22:32) I declare that the Church has no authority whatsoever to confer priestly ordination on women and that this judgment is to be definitively held by all the Church’s faithful.