Yes it does
Yes, you can add beast forms to your Wild Shape repertoire of beasts seen by casting conjure animals. The spell explicitly says the conjured creatures literally are beasts, and a creature of the type beast is all Wild Shape needs you to see in order to add its form to your repertoire.
Though someone might by tempted to quibble that they're not real beasts because they're really fey spirits clothed in the shape of beasts, look at it this way: First the Druid conjures a bunch of spirits that take on the form and behaviour of the real beasts they look like. The creatures so conjured proceed to behave and look exactly like the real thing. What better opportunity is there for a shapechanger to learn a new form to wear, than to see a nature spirit do the exact same thing as they're wanting to learn to do?
But it's of limited use
What you might actually run afoul of is limitations on metagaming, or a DM whose setting doesn't include just any creature you can think of (even if it's in the Monster Manual).
- A DM who wants to limit metagaming would be within their rights to ask you to justify your choice. If you try to summon a Giant Owl but your druid has never seen one before, a DM could easily say "How do you know those exist? You've never seen one. How is your druid "choosing" an animal (s)he has never seen or heard of before?"
- A DM who has developed a custom setting isn't straightjacketed by the Monster Manual and doesn't have to include everything in it. Giant Owls might not exist in a DM's campaign.
This also means that this is much less of a loophole than it might seem — after all, how big is the difference between the set of creatures a druid has personally seen and the set of creatures the druid knows about well enough to deliberately try to conjure? I can't imagine it's a very large number.
But in principle, yes, a conjured animal inhabited by a fey spirit is plenty to learn that form from. Just mind that, if you can conjure a particular animal, it's highly likely your druid has already seen it anyway. This makes this method of acquiring new forms both limited in utility and not much of a loophole to worry about, either way.
No, you aren't creating
As you've stated, the requirements for the Druid abilities require you to summon or conjure a beast or fey - something that Giant Insect is not doing (as you've quoted). Using plain english does not override the language used in the spell description.
Jeremy Crawford also supports this interpretation to show Rules as Intended:
Twitter Question Would Giant Insect Count? Yes I know the wording says trasnform.
Crawford No
Best Answer
Conjured animals would gain temporary hit points
The Bear Spirit option of the Shepherd Druid's Spirit Totem feature states (XGtE, p. 23):
There is no limit to the number of allies this may affect; they simply need to be within the aura (a 30-foor radius).
There already exists the question "Does a familiar count as an ally?", and the most upvoted answer there states that yes, it does count as an ally. Note that "ally" is not a defined game term, so it comes down to its standard English usage; I would certainly call animals made by conjure animals allies, especially since the spell states:
Though this combo is strong, effects at that level may still kill the boars. For example, a fireball spell dealing 8d6 (28) fire damage would kill the boars, with or without the temporary hit points (on average).
For some math (from AnyDice), the odds of rolling an 11+ on 8d6 is nearly 100%; the odds of rolling 21+ is still a 93.93% chance. However, if they pass the saving throw, then you need to roll 22+ normally, a 90.93% chance, and a 42+ with the THP, a mere 0.18% chance.
Also, conjure animals is a concentration spell, so if the conjured creatures become a challenge for the enemy, they have a pretty good reason to now target you.