You are right to say that Islam changed and evolved during the life of the Prophet (pbuh), but then you overlook his final sermon when he said it was now complete. It’s like making a scuplture. It takes different shapes while it is being made, but then stays in its final shape once complete.
Those fasting rules did not change during the lifetime of the Prophet (pbuh), when he expanded the area under his direct rule to all of the Arabian peninsula, including agricultural areas (such as Hijaz and east coast oases, as well as Yemen) and industrial areas (yemini textiles were famed). This shows that the fasting rules he laid down were for more than just Meccans.
Today, 1.3 billion Muslims living in places varying from the frozen north of Canada to the hot wastes of the Sahara through the the very tip of Africa fast as required. The very fact that fasting hasn’t emerged as a widespread health hazard in this population also backs up that the fasting rules laid down in Mecca can still be followed through the world without harm. Indeed, those same rules also specify that if you are in a position where fasting would cause you harm then you are excused .
The view that women cannot work is a minority view amongst scholars. There are many, many fatwas clarifying that is it permitted. In fact, you can see in many Muslim countries from Morocco to Malaysia, how active mainstream Islamist movements are in condemning public immorality, yet they don’t say a word against the women working in those countries.
In Pakistan, the main Islamist movement, the Jamaat-i-Islaam, even regularly boasts of how many women professionals are joining the party to help it achieve its goal of making an Islamic nation.
Your example is bad - even you yourself don’t say that he made Taraveeh obligatory but then stopped it.
Islam is open to interpretation by those who have studied it and its sources in depth, and in fact many prominent scholars have opposed codification of Islam and defended the need to allow it to always be open to interpretation. Imam Ahmad bin Hanbal, the founder of the Hanbali fiqh, was one such person.
However, interpretation does not allow changing of the words Quran and the Hadith/Sunnah, and it does not allw you to go against anything explicitly mentioned in the Quran and Hadith/Sunnah.
That being said, there have been different interpretations of Islam over different times and places.
A number of examples include how Imam Shafi (founder of the Shafi fiqh) changed his viewpoint on a number of issues after moving from Iraq (an urban sociaty) to Egypt (a rural society). The interpretation which has had made of the Quran and Hadith in one location didn’t easily apply to the life in another.
Another, more extreme, example comes from Turkey, where in during the early Ottoman era there were regular civil wars after sultans died when their sons would wage brutal civil wars to take control with thousands of Muslims dying as a result. Turkey’s scholars interpreted Islam at the time to issue a fatwa saying that to save lives, it was halal for a a Sultan to imprison and murder his brothers upon taking power. Later on, when constitutional succession was established, this interpretation was abandoned.
My point is that Islam already has leeway to adapt to changing societal needs, and already has done so.