[numpad0]

N-1 only flew 4 times. Flight 5 of N-1 was supposed to use upgraded NK-33 engines.

X-33 never got to test flight because the engineer minded NASA director kept pushing an unrealistic technical goal.

Besides, SS still hasn't gotten its payload system working.

Are those that dissimilar to how SS program is going?

[kataklasm]

Yes, they are. Starship has proven multiple novel engineering approaches and technologies. Examples: 1. catching the booster in the air to save on landing gear weight and complexity 2. firing 33 engines simultaneously in a tight cluster 3. the only large scale production and use of CH4-fuelled engines (all other CH4 engines have only been fired a handful of times at most)