The present perfect conceptualizes the past thing from the point of view of its relation to the present.
Having eaten pumpkin pie, I know what it tastes like.
My present knowledge is the result of eating pumpkin pie at some point prior to "now". The eating might have taken place 1 second ago or 1 year ago or 10 years ago. I might have some unfinished pie on a plate in front of me. All we know from the tense is that I am someone who ate some pumpkin pie at some time in the past.
With "having lived", if you said this and only this:
Having lived in India, I am familiar with the cuisine.
all that can be concluded from the statement is that you lived in India at some period in the past. It could be last week, or last year, or for the past 20 years. You are a person who can truthfully say "I lived in India". You might live there still.
Now, let's see if we complicate things by adding "all my life".
Having lived in India all my life, I am familiar with the cuisine.
All my life does not exclude the present moment; nor does it necessarily include it. You can easily say, as someone who has emigrated to Antarctica, "I lived in India all my life. But now I live here at the South Pole. Aren't the freezing temperatures refreshing?"
So, we cannot conclude from the statement whether you are living in India now, or have moved elsewhere. All we know is that you are a person who can claim to be someone who, at some time in the (recent) past, had been living in India since birth. all my life does not exclude the present but it does guarantee it: a person who had been born in India and who had lived there until very recently, could say "Having lived in India all my life..."
So, yes, you can say "having lived" whether you have moved away, or you still live there.
Firstly the rule about uncountable nouns is not right and needs some expansion. Uncountable nouns can either be singular or plural in form. Examples of plural ones include jeans, pants, glasses (spectacles) and goods. They use are rather than is in your example.
For your question I would say "is" is the correct usage. In order to use "are" there needs to be some grouping of the two and "many" being applied to the former and not the latter breaks that.
Best Answer
It can be decomposed according to rules you’re familiar with.
“People all over the world” means people who are scattered and located all over the world. It could be understood as “People, who are all over the world, ...”.
“People from all over the world” means people who originated from or were born in places all over the world. It could be understood as “People, who are from all over the world, ...”.
Both cases are of a noun being modified by an adjective (a prepositional phrase, in the second) that directly follows it.