First use of “learnings”?
Solution 1:
The answer appears to be in 1483, at least in the plural.
The OED gives sense 2 of the verbal noun learning five different subsenses, of which at least the last (and perhaps others; it is subclear) is marked obsolete. I include a few citations in the plural, with bold emphasis mine.
2. What is learnt or taught:
- a. a lesson, instruction;
- 1483 Caxton G. de la Tour cxxxvii. M vij, — The thre enseygnementes or lernynges whiche Cathon gaf to his sone.
- 1611 Shaks. Cymb. i. i. 43 — The king..Puts to him all the Learnings that his time Could make him the receiuer of.
- b. information or direction;
c. the ‘teaching’ of a person; a doctrine; also, a doctrine or maxim in law;
- 1549 Coverdale, etc. Erasm. Par. Rom. 34 — To expounde unknowen learnynges.
- 1560 Pilkington Aggeus C ij (Matt. xv. 9), — Teaching learninges which are the commaundementes of men.
- A. 1626 Bacon Max. & Uses Com. Law Pref. (1636) 2 — Particular and positive learnings of lawes doe easily decline from a good temper of justice.
d. a branch of learning; a science;
- 1570 Billingsley Euclid xi. xi. 315 — It is no rare thing in all learninges..to haue one thing more generall then an other.
- 1605 Bacon Adv. Learn. i. vi. §13 (1873) 49 — He did send his divine truth into the world, waited on with other learnings.
- 1613 Sir H. Finch Law (1636) 6 — The rules of Reason are of two sorts; some taken from forreigne learnings, both diuine and humane.
- e. an acquirement. Obs.
My personal impression is that the modern use sounds like annoying business jargon or non-native speaker use, and I would not use it myself.
Solution 2:
OED has three citations for learning meaning lesson, but it notes it's obsolete.
†2. What is learnt or taught:
a. a lesson, instruction.1362 Langland Piers Plowman A. i. 174 That nis no treuthe of trinite but..a leornyng for lewed men, the latere forte dele.
1484 Caxton tr. G. de la Tour-Landry Bk. Knight of Tower (1971) cxxxvii. 183 (heading) The thre enseygnementes or lernynges whiche Cathon gaf to his sone.
a1616 Shakespeare Cymbeline (1623) i. i. 43 The king..Puts to him all the Learnings that his time Could make him the receiuer of.
The latest citation is Shakepeare when he wrote it in 1616 (published 1623).