本来 (originally / at first)

Change of plan

• You were going to spend the holiday in Yunnan, but then your cousin invited you to Hainan.
• I我wǒoriginally本来běn láiwant to想xiǎngto go去qùYunnan province in…云南yún nán，later后来hòu láito go去qù(completed / change)了leHainan Province, in the…海南hǎi nán。 — "I originally wanted to go to Yunnan, but in the end I went to Hainan."

originally本来běn lái = originally, at first

• originally本来běn lái describes the original plan or situation, usually before something changed.
• It goes after the subject (or at the start): he他tāoriginally本来běn láiwas是shìa doctor医生yī shēng，later后来hòu láibecame当dāng(completed / change)了lea writer作家zuò jiā.

he他tāoriginally本来běn láiwas是shìa doctor医生yī shēng，later后来hòu láibecame当dāng了lea writer作家zuò jiā。

Plans that changed

• I我wǒoriginally本来běn láiunexpectedly不想bù xiǎngcome来lái，but可是kě shìfriend朋友péng yǒudefinitely一定yí dìngwant / will / need要yàoI我wǒcome来lái。 — "I didn't really want to come, but my friend insisted."
• originally本来běn lái often pairs with later后来hòu lái, but可是kě shì or but但是dàn shì to show the change.

I我wǒoriginally本来běn láinot不bùwant to想xiǎngcome来lái。

The second meaning: of course

originally本来běn lái versus so it turns out原来yuán lái

• Both can mean "originally": originally本来běn lái / so it turns out原来yuán lái(modifier / structural particle)的deplan计划jì huà.
• Only so it turns out原来yuán lái announces a discovery: so it turns out原来yuán láiwas是shìyou你nǐ！ — "Oh, it's you!" originally本来běn lái cannot do this.

so it turns out原来yuán láiit's是shìyou你nǐ！

Recap

Read the full reference: HSK 4 grammar — Adverbs.