[O]ne thing for folks to remember is that Buddhism did change and evolve over many centuries, as it passed from culture to culture in Asia. The Buddha lived 2500 years ago in ancient India, whereupon the philosophy passed to China 1000 years later, and then to someone like Master Dogen who lived about 1000 years after that in medieval Japan. You and I live in the strange world known as the 21st century. Certainly, some changes arose along the way in some important interpretations and outer forms. For example, the Chinese made Zen Practice very Chinese, the Japanese very medieval Japanese, and now we are making it very Western.
For example, when Buddhism came to China it was heavily influenced by, and pretty much merged with, Taoism (not to mention that it was already "Mahayana Buddhism" by that time, a very different flavor from the original). The result was this little thing we now call "Zen Buddhism". So, congratulations, we are already "Taoists" and "Mahayana Buddhists" ... not just "Buddhists". When it got to Japan, the Japanese added Japanese culture to it. In the West, we are now making some very good changes (although we have to, of course, try to avoid bad changes). These good changes include equality of the sexes and a greater emphasis on lay practice.
However, the Heart of the Buddha's teachings ... the Four Noble Truths, the Eightfold Path, Non-Self, Non-Attachment, the Middle Way, etc. etc., ... All are here now as much as there then!!