Is Tom seriously the one with the most Starfleet experience here?

"Well... I wasn't on the Exeter for very long, but nothing nearly this exciting happened there. So far on Voyager two really scary things have happened: the Caretaker thing, and this."

You forgot Laurence- oh wait he said scary, nevermind.

"And this is the captain's first post as captain as well, isn't it?" he asks, cutting at the heart of the general air of ignorance he perceives.

... And belatedly adds, "I thank you. Both of you. For my own rescue, at a minimum, though that is little enough against that of the rest of the crew."

And, he expects, it is even more challenging to save the ship when most of the crew is so inexperienced and half of them hate the other half.

"You're welcome."

Well, he's not a total jerk at least.

"Not everybody's new to this. Hasn't Tuvok been in Starfleet for like a hundred years?"

What a rude response from Torres. He'll let it pass.

Laurence looks amused. "A hundred years, is it? Perhaps it must seem so to one so new to Starfleet as yourself." He's starting to feel a little more comfortable with Kim, enough for this very light teasing about the other ensign's obvious exaggeration.

"Harry, what are you doing? You didn't tell him anything about Vulcans?"

He turns to Laurence. 

"Vulcans live, what, 200 years or so? I don't actually know anything about Tuvok's career but it's entirely possible."

"Harry's sort of right. He joined about 80 years ago but actually left pretty soon after for a long time. I think he's got something like 30 years in Starfleet?"

Not knowing Tuvok's biography would have gotten her arrested if not for the Caretaker thing, so she's done some reading after the fact.  This was not, in fact, helpful, since she is very unlikely to be betrayed by Tuvok again, but it still seemed like the thing to do.

"Vul... kens?" he says, hesitantly.

Then: "Do you... That is, does the term 'year' still refer to one revolution of the Earth around the sun?"

Tom, barely containing himself, stands up, slaps Harry on the back, and starts pacing.

He spares a second to give Tom a glare. Looks like Laurence didn't pick up on aliens after all.

"So, I think I forgot to explain something important."

"Not all the people in the federation are human. There are 173 member species," they make you learn that in elementary school "all of which originate on their own planet."

"Tuvok is a Vulcan, which is to say, he's not human. B'elanna is half Klingon. There are several other species on board."

B'elanna doesn't really love being the example alien here but it doesn't seem reasonable to object.

"Chell's a Bolian!" Tom contributes, helpfully.

Laurence is so mortified asking this that he wants to sink into the floor, but. Somehow he can't help himself. "Half... um... Klingon?"

"Well, when a mommy Klingon and a daddy human love each other very, very much..."

Probably this isn't a useful response, but she can't really bring herself to care.

This response is, regrettably, very useful. He hates this so much. Why did he ask that.

He's never asking any questions again.

Still blushing furiously, he thinks for a moment.

"I suppose," he says very slowly, "it is sensible that other... er... people," he looks around to verify that they think that's the right word, "would be so similar to humankind, since surely God made them all in his own image."

He's trying his best to be conciliatory here.