Would something like Satyr Grovedancer or something that has "When ~ enters the battlefield, put a +1/+1 counter on target creature" trigger Heroic?
It has the keyword target, but does it count as an ability or as part of the spell that targets? I guess this goes likewise for any ability that occurs when a card enters the battlefield.
No, Heroic cards specifically state "whenever you cast a spell that targets [this card]". Abilities are not spells. Here is the definition of a spell:
111.1. A spell is a card on the stack. As the first step of being cast (see rule 601, “Casting Spells”), the card becomes a spell and is moved to the top of the stack from the zone it was in, which is usually its owner’s hand. (See rule 405, “Stack.”) A spell remains on the stack as a spell until it resolves (see rule 608, “Resolving Spells and Abilities”), is countered (see rule 701.5), or otherwise leaves the stack. For more information, see section 6, “Spells, Abilities, and Effects.”
111.1a A copy of a spell is also a spell, even if it has no card associated with it.
The Satyr Grovedancer's ability goes into the stack when it enters the battlefield which doesn't happen until after it was cast (and subsequently resolved). The effect is on the stack, but is not spell because it is not a card being cast (or a copy of a spell).
Instants and sorceries that say "target" will trigger heroic. Enchantment auras will as well even though they do not say "target" because of rule regarding auras:
113.1b Aura spells are always targeted. These are the only permanent spells with targets. An Aura’s target is specified by its enchant keyword ability (see rule 702.5, “Enchant”). The target(s) are chosen as the spell is cast; see rule 601.2c. An Aura permanent doesn’t target anything; only the spell is targeted.
Anything else will be an ability and thus do nothing.
