1Indicates how something was, or was meant to be, from the very beginning — "originally" or "properly speaking."
本来なら今日中に終わらせるはずだった。
This was originally supposed to be finished today.
この道具は本来、料理用に作られたものだ。
This tool was originally made for cooking.
本来の目的を忘れて、余計なことに時間を使ってしまった。
I forgot the original purpose and ended up wasting time on unnecessary things.
彼は本来、几帳面な性格だ。
By nature, he has a meticulous personality.
2Describes a property something has essentially or intrinsically, by its very nature.
人間は本来社会的な生き物だ。
Humans are essentially social creatures.
その薬は本来、外用のために作られている。
That medicine is intrinsically formulated for external use.
本来の性格が次第に表れてきた。
Their true nature gradually came out.
3Refers to what is proper, rightful, or normal — as in "the proper procedure" or "properly speaking, one should..."
本来の手続きに従わなければ、処理は進められない。
If you don't follow the proper procedure, the process can't move forward.
その問題は本来ならば上司が判断するべきだ。
Properly speaking, that issue should be decided by the boss.