Avira, not only has the application of halacha changed, our religion has undergone massive change in the past
One example is divorce. Originally, a man could divorce his wife unilaterally;now she must agree.
If Jew ( an anachronism ) from the early years of the first Bais Hamikdosh were to come back to life now, he wouldn’t recognize we call Judaism. In his tim e:
1. There were no shuls
2. There were no siddurs
3. There were no religious rituals outside of Jerusalem
4. He wouldn’t be able to read the Torah. Until the Babylonian
Exile, Hebrew was written in Paleo-Hebrew script, not the
Aramaic block letters that Ezra introduced. The Samaritans,
brought into Israel by the Assyrians , copied our Sefer Torah
and theirs is still written in Paleo-Hebrew.
There is a lot more