My link on post 6 does a very good analysis of Ussher. The man was amazingly brilliant to throw his works out lightly. You see the world as very old but Jesus obviously believed the flood was a real event that took place and the collective memory of mankind retains aspects of it around the globe. That cataclysmic event made the earth look old.
Num 23:19 God is not a man, that he should lie; neither the son of man, that he should repent: hath he said, and shall he not do it? or hath he spoken, and shall he not make it good?
He didn’t lie. He couldn’t, it’s not in His nature.
Since there is no evidence of a world wide inundation within human memory then you must be misinterpreting what He said.
The world is completely covered with the evidence of the flood. It is the dominant characteristic of our geography.