First of all please learn how to use the quote function, it's not hard and makes your posts much easier to read and reply to. Thanks!
Post Eden humanity by its very nature is "fallen" ...
Do you mean this in a literal sense?
Wrong. Any legal tradition has 1. Basic precepts or inalienable rights as in the amercan or french constitutions or in our unwritten one. Indeed most systems regard them as universal and self evident... and 2. developing and changing case law based on needs of certain times and circumstances.
Sharia like any tradition has these two aspects
This sounds like a lot of sophistry, "our unwritten one" seems especially problematic, not to mention "universal and self evident". For example I hold the right to marry any person regardless of creed, race, religion, etc. as self evident, same goes for LGBT rights, the right to blaspheme or the right to leave any religion. Can you please give a few examples and possibly fatwas as to how certain barbaric aspects of Sharia were overturned (for example: free marriage, LGBT rights, fair inheritance, free religion, etc.). Problem is that there is absolutely nothing in Sharia that would further advance UK legal system.
"CLR James, like most anti-imperialists over the past two centuries, recognised that all progressive politics were rooted in the "Western tradition", and in particular in the ideas of reason, progress, humanism and universalism that emerged out of the Enlightenment. The scientific method, democratic politics, and the concept of universal values - these are palpably better concepts than those that existed previously, or those that exist now in other political or cultural traditions. Not because Europeans are a superior people, but because out of the Renaissance, the Enlightenment and the scientific revolution flowed superior ideas.
Many of the ideas we call "Western" are in fact universal, laying the basis for greater human flourishing. The catch is not to reject "Western" ideas but to reclaim the best of them for all of humanity."
People are potentially equal but cultures are not, because if they were the very idea of social and moral progress would be meaningless. It would be far better if everyone had the chance to live in the type of society or culture that best promoted human advancement.
Which Islam certainly doesn't, in fact it fails miserably in just about any aspect.
*Disclaimer
I am talking about the "literal" Islam as practiced by the large majority of Muslim. In case you are a Sufi the likes of The Tailor I apologise in advance.