The origin of the sense “novice” is from fruit and vegetables which when are green, are generally unripe, immature:
From c. 1200 as "covered with grass or foliage." From early 14c. of fruit or vegetables, "unripe, immature;" and of persons, "of tender age, youthful, immature, inexperienced;" hence "gullible, immature with ...
The OED has Shakespeare’s Othello (a1616) as the first green-eyed monster:
O beware iealousie. It is the greene eyd monster.
Shakespeare earlier used monsterless green-eyed to allude to jealousy in The Merchant of Venice (1600):
Shyddring feare, and greene-eyed iealousie.
The OED says this is "apparently arising from association ...
Jealousy, the green-eyed monster
In Othello, Act 3, Scene 3, Iago says
O beware, my lord, of jealousy;
It is the green-eyed monster which doth mock the meat it feeds on.
Source: No Sweat Shakespere
The green novice
I've always thought of this in terms of a growing plant. The newest leaves and sprouts are often green. But as the plants mature, the sprouts ...
Meta comment: Right now you've really asked two completely different questions ("green = envy" and "green = novice"). It would have been better to split them up — and you would have gotten more fake Internet points by doing so, too! Anyway, I'm going to answer only the "envy" question.
Original source: The Guardian 2021-02-14.
I would personally associate green for novice more with young woody plants than with vegetables. Note (medical) 'greenstick fracture', which is the type of bone fracture that parallels how young, 'green', wood breaks (stays connected) rather than the breaks that match old 'brown' (my word) wood (Snaps across). Likewise 'green shoots' for new growth.
That is ...
To complement @Sven Yargs' excellent answer:
TL;DR: The name appears to have originated as Kuklux (after kuklos = circle), later Kuklux Klan, then Ku-Klux Klan, and finally Ku Klux Klan. The name first appears in the Pulaski, Tennessee, newspaper because that town is where the organization was started.
The August 24, 1901, Peninsula Enterprise, a newspaper ...