So your players aren't biting at those hooks you set.
Or perhaps they are biting...just too easily. They don't bother to do any oblique thinking. They willingly railroad themselves into a plot. They wait for you (the DM) to hand deliver them a quest, but you want them to explore with some self-direction.
Your problem is that your world has no detail.
Dedicated players cannot help but be intrigued by world details. But the details that DMs usually put in don't spark action, or generate questions.
For example: "You walk into the next room in the dungeon, a forty foot by thirty foot by ten foot chamber with more dark stone walls and carved floors. It isn't as musty as the previous rooms. There is a wooden table with matching chair in the center of the room, a goblin body is sprawled across the table with a roughly crafted dagger sticking out of its back. There are six silver pieces in the goblin's pockets. On the other side of the room is another wooden door."
You can probably pictures that room well, and you would be confidently interacting with it if you were a player. But you wouldn't get anything from it except "you should probably continue into the next room, and there are other things alive down here, if you didn't already know that."
But that isn't enough. Where are the things that the players will hold onto when they leave the dungeon? Where are the tiny hooks into future adventure?
The answer is: on a half dozen random tables that you need to generate now. Like, right now. d100s.
Table 1: Random names. Each entry should have one humanoid name and one monstrous one.
Table 2: Motives. A big list of things this creature or NPC could be doing/involved with.
Table 3: LOOT. A list of stuff that enemy or NPC might have on them.
Table 4: Details. Roll with the LOOT table to get unique treasure every time. Ex: "Has an elvish rune on it."
Table 5: Dungeon Motifs. Yeah, it's dwarvish. But maybe it was built by dwarves that had giants as slaves...
Table 6: PLOT TWIST. A list of random things that an NPC or monster could do to mix things up.
The point of these tables is that, without them, the DM rarely fills in these blanks, even though they would always be filled in if this were real. That dagger in the goblin's back will just be a shitty dagger if not for these tables. But a shitty dagger with an elvish inscriptions? (Hell, make a random inscription table...) Now that's interesting and worth questing about.
Every time you, as the DM, put a goblin in the dungeon that doesn't have any reason to be there other than as an encounter for the PCs, you've wasted time and energy. But giving each goblin a story while you prep for the session would be ridiculous. That's what the tables are for. If the PCs are in too much of a rush to loot and examine that dead goblin, then that's that. Other things are more interesting right now, and you can leave that goblin as "just a goblin." But start encouraging your PCs to explore the details.
You'd be surprised at the level of storytelling that emerges from stupid details.
Think about it. Those six silver pieces in the goblins pocket? Why are they there? Money doesn't just appear in people's pockets (unfortunately). That goblin did something to earn those silver pieces. Maybe he found them on the ground while heading back to the dungeon after being kicked out of his goblin group. Maybe he killed someone for pay. Maybe he cheated in a card game, and his opponents let him keep the silver, but put a blade between his shoulder blades as a parting gift. That could be another table: How did this guy get this money, d100. You get the drift.
Just be ready to fill in the details when the PCs want you to, but don't do random details off the top of your head. Put them together earlier, and craft them to be sure every single detail is a stepping stone for more adventure.