As It is said, that everyone has thea greatest ideas at least once in atheir lifetime, but a skerrick of people do ever act on them. It is said that everyone has a great idea at least once in their lifetime, but a skerrick of people ever act on them.

Subtleties. "As it is said" is "Like it is said", you'd say it if you were sort of saying "It is said and it is true". "As it is said, English is difficult to explain" - "English is difficult to explain, like people famously say it is". You might mean this, but without context simply "it is said" seems likelier. "do ever act" feels sort of mythological or antiquated. It actually sort of works with "skerrick", which is a word you've apparently used correctly but that I have never heard before in my life. Makes it sound like this a provincial proverb.

As It is said,often said that everyone has the greatest ideas at least once in a lifetime, but a skerrick of people do ever act on them. It is often said that everyone has the greatest idea at least once in a lifetime, but a skerrick of people do ever act on them.

I don't know what a "skerrick" is... But as a native English speaker, one way I would write this sentence is "but a minority of people ever act on them" or "but a minority of people ever take initiative". I think that's what you want to express. :)

A cavalcade of emotions swirled through me while reading your post. A cavalcade of emotions swirled through me while reading your post.

Consider "while I was reading" or "while I read" - it's clear here what you mean but this structure can be ambiguous, there's no grammar to say whether it was you or the emotions that were reading.

A cavalcade of emotions swirled through me while reading your post. A cavalcade of emotions swirled through me while reading your post.

I've never heard anyone use the word "cavalcade" like this before. I think I would write "A cascade of emotions rushed through me while reading your post" or "A whirlpool of emotions swirled through me while reading your post".

One’s dignity should never be trampled over by the whimsical attitudes of people. One’s dignity should never be trampled over by the whimsical attitudes of people.

People being plural, they have attitudes. You can have "the people", and you would have "the attitude of the people", but here it's simply a plural rather than a collective noun.