"create, fashion, form," Middle English shapen, from Old English scapan, past participle of scieppan "to form, create, make out of existing materials; bring into existence; destine" (past tense scop, often used of God).
This is reconstructed to be from Proto-Germanic *skapjanan "create, ordain" (source also of Old Norse skapa, Danish skabe, Old Saxon scapan, Old Frisian skeppa, Middle Dutch schappen "do, treat," Old High German scaffan, German schaffen "shape, create, produce"), from PIE root *(s)kep-, forming words meaning "to cut, scrape, hack" (see scabies), which acquired broad technical senses and in Germanic a specific sense of "to create."
Old English scieppan survived into Middle English as shippen, but shape emerged as a regular verb (with past tense shaped) by 1500s. The old past-participle form shapen survives in misshapen.
The meaning "to form in or with the mind" is from late 14c. Also by late 14c. as "prepare, get ready." The sense of "give a definite form to" is by 1580s. Specifically as "give direction and character to" (one's life, conduct, etc.) is by 1823.
The phrase shape up (v.) is literally "to give form to by stiff or solid material;" attested from 1865 as "progress;" by 1938 as "reform oneself, pull oneself up to a standard;" alliterative variant shape up or ship out is by 1951 in the newspapers, said to be Korean War U.S. military slang, with a suggestion of "do right or get shipped up to active duty."
-able
common termination and word-forming element of English adjectives (typically based on verbs) and generally adding a notion of "capable of; allowed; worthy of; requiring; to be ______ed," sometimes "full of, causing," from French -able and directly from Latin -abilis. It is properly -ble, from Latin -bilis (the vowel being generally from the stem ending of the verb being suffixed), and it represents PIE *-tro-, a suffix used to form nouns of instrument, cognate with the second syllables of English rudder and saddle (n.).
A living element in English, used in new formations from either Latin or native words (readable, bearable) and also with nouns (objectionable, peaceable). Sometimes with an active signification (suitable, capable), sometimes of neutral signification (durable, conformable). It has become very elastic in meaning, as in a reliable witness, a playable foul ball, perishable goods. A 17c. writer has cadaverable "mortal."
To take a single example in detail, no-one but a competent philologist can tell whether reasonable comes from the verb or the noun reason, nor whether its original sense was that can be reasoned out, or that can reason, or that can be reasoned with, or that has reason, or that listens to reason, or that is consistent with reason; the ordinary man knows only that it can now mean any of these, & justifiably bases on these & similar facts a generous view of the termination's capabilities; credible meaning for him worthy of credence, why should not reliable & dependable mean worthy of reliance & dependence? [Fowler]
In Latin, -abilis and -ibilis depended on the inflectional vowel of the verb. Hence the variant form -ible in Old French, Spanish, English. In English, -able tends to be used with native (and other non-Latin) words, -ible with words of obvious Latin origin (but there are exceptions). The Latin suffix is not etymologically connected with able, but it long has been popularly associated with it, and this probably has contributed to its vigor as a living suffix.