You have very good pronunciation overall!
However, you have some problems with word/sentence stress. For example,
have been held = have been HELD -> "Been" is usually reduced to "bin" in a British accent and it's usually not stressed.
ancient festivals = ancient FESTIVALS -> "Noun" is more important than adj.
some are religious, some seasonal, and some for special people = some are RELIGIOUS, some SEASONAL, and some for special PEOPLE -> "Religious" is more important than "some". And when you don't stress "some", you keep it that way for the rest of the series.
Knowing where to stress and where to reduce vowels is absolutely important for natural-sounding speech.