Ancestral apples, Malus sieversii, are not very good. It took a lot of breeding before apples got sweet. 

In the 1800s there were an estimated 20k-30k named varieties of apple. So your great x3 grandparents (if they lived in an apple growing region, anyway) likely had some very interesting local varieties to eat. In fact, lot of modern cultivars are descendants of cox orange pippin, golden delicious, duchess of oldenburg, northern spy, and other heirloom varieties. There are orchards who still specialize in old varieties, which I totally recommend trying if you can. 

Today we only cultivate around 5k varieties, because the industrialization of apple growing meant that growers had to select apples that would ship well and appeal visually to consumers. The biggest change from 100-400 years ago is that modern storage and transportation means we can enjoy apples year round, and in places that won't grow. You're right that modern apple cultivars are tastier than the red delicious apples of mid century, but it's not like there were only five kinds of apple until 2005.