The meaning of Old is gold is that whatever is old is as important as gold. We should not think or brand any thing old as a waste. Even though this proverb is short, it has a very descriptive/lengthy/valuable meaning.
The foundation for all the new things in the present world was laid in the olden days and what we are getting at present is all the updated/improvised ones of the old inventions which form the base of the new ones. So we need to value the old things much as these are the basics of learning new things.
Old songs with their sweet melodies, old sculptures standing tall, old friends etc, are all much more precious than gold. From practical to aesthetic value they are very much valuable just like gold. When a thing becomes old it is more valued.
Memories are called "Golden memories"! Usually people of any time feel good about their past, how life was so simple (no matter whether they are saying it in 1000 AM or 2100 AD!! They feel nostalgic about their past, childhood etc.
Same goes for people also. With age they get more experience compared to youngsters and that experience is as valuable as gold.
Perhaps an inner meaning of this saying "Old is gold" could be "Don't disrespect/neglect your elders just because they are old but do take care of them like they are as precious as gold" ❤️
~Virgo
I definitely agree with you dear. Just like keeping the old memories i considered it a golden treasure.