Are some Bible verses not meant for us?

I often see people quote scripture like Deuteronomy 31:8

”Do not be afraid or discouraged, for the Lord will personally go ahead of you. He will be with you; he will neither fail you nor abandon you.”

However this was Moses speaking to Joshua when he couldn’t cross the Jordan and go with him to fight the many nations ahead of them. I know some people say this speaks to the nature of God, but what about verses like Jeremiah 15:6 that says:

”You have abandoned me and turned your back on me,” says the Lord. “Therefore, I will raise my fist to destroy you. I am tired of always giving you another chance.“ ‭‭

How come some verses apply to us and others don’t. Do we pick and choose which ones we like and which ones we don’t? I’m sure I’m missing a lot of context with Jeremiah 15:6. I’m just curious how you discern what verses are meant for us today and what are not?

Thank you