The word 'manuscript': Somewhere I read 'Manu' is a Latin word which means 'hand'. How could this word be Latin as it originated in India or say Ancient India?
I will let pass the lack of proof for the affirmation that
it originated in India or say Ancient India
How did the word appear to India? Let's greet Proto-Indo-European,
is the linguistic reconstruction of the hypothetical common ancestor of the Indo-European languages, the most widely spoken language family in the world.
Note that this is an hypothesis, and the reconstruction is based in comparing common terms between languages. Not only that a word appears now in different languages, but also that there is proof of use in many of the Indo-European languages1
In particular, an etymological dictionary gives, after a 2 minute search:
Proto-Indo-European root meaning "hand."
It forms all or part of: amanuensis; command; commando; commend; countermand; demand; Edmund; emancipate; legerdemain; maintain; manacle; manage; manciple; mandamus; mandate; manege; maneuver; manicure; manifest; manipulation; manner; manque; mansuetude; manual; manubrium; manufacture; manumission; manumit; manure; manuscript; mastiff; Maundy Thursday; mortmain; Raymond; recommend; remand; Sigismund.
It is the hypothetical source of/evidence for its existence is provided by: Hittite maniiahh- "to distribute, entrust;" Greek mane "hand," Latin manus "hand, strength, power over; armed force; handwriting," mandare "to order, commit to one's charge," literally "to give into one's hand;" Old Norse mund "hand," Old English mund "hand, protection, guardian," German Vormund "guardian;" Old Irish muin "protection, patronage."
Usually, the more "basic" the word, the more probable a common origin is. The names for "water" in a lot of languages sound notably similar, for example.
Short words are more likely to have phonetic coincidences in other languages, and sometimes its semantics may be close enough. This often leads to confussions and false etymologies (Portuguese obrigado and Japanese arigato).
That said, the data provided by the etymological dictionary seems rather convincing to me.
1Which, as you could guess, covers a lot of the languages currently spoken in Europe, India and in between.