Thanks to OZ for this.
When I was in college, the Jazz Singer was 40 years old. It seemed ancient and primitive.
Body Heat is now more than 40 years old, and it doesn’t seem that dated. On the other hand, films that are 60 years old (1961) seem quite ancient, in both technology and attitude. So I guess maybe 60 is the new 40.
Modern film making began in 1967 when they dropped the Hays code and started making films like The Graduate. Before that movies had to be so censored that they became very unrealistic. We see similarities in music as late 60s and 70s music is still very popular today. The removal of corporate control and censorship was key. The 60s are somewhat of an artistic renaissance.