Yes, we have our official kohanim descended from Aharon Hakohen from the Tribe of Levi. They are the official kohanim of the Jewish people.
But bnei Yisrael are the kohanim of general humanity.
Every Jew is a specially chosen servant of Hashem (which is something Rav Miller says to think about as you eat your matzah at Leil HaSeder) and this is a huge privilege that many Jews don't appreciate as much as we should.
Matzah is generally the official Temple food of the Kohanim.
So when Hashem commands us to eat matzah, He is emphasizing our special role in the world. He wants us to really FEEL our privilege.
The truth is, if we maintained constant cognizance of this fundamental fact, we would automatically behave so much better, both regarding derech eretz and regarding the avoidance of sin.
Seeing Yourself as If You Personally Left Mitzrayim
It was preordained and meant as preparation for receiving the Torah.
We needed the trial of Mitzrayim to become the nation Hashem meant us to be.
And in order to understand that, and also to fulfill our mitzvah of viewing ourselves as if we personally just left Mitzrayim now, Rav Miller offers us a detailed & compelling visualization of how that actually was, a description worded for today's modern mind, starting on page 9 of the PDF until page 13.
(Also, please read the Q&A on the last page of the PDF regarding what we can learn from the Korbon Pesach.)
Even if you don't manage to read pages 9-13 before Shabbat, try to take a look at it sometime before Leil HaSeder so you can have a vivid picture in your head of Egyptian bondage.
Rav Miller notes that a person only has the chance for 120 Seders in his or her life.
(Maybe that's 240 if you live outside of Eretz Yisrael and keep 2 days. Actually, I remember how shocked & a bit dismayed I was when first coming to Eretz Yisrael & keeping only 1 Seder. "But then you don't have the chance to get right anything you messed up at the first Seder!" I said. But nope, in Eretz Yisrael, you only get one chance to do it right. You have to give that first Seder your all, even though that's the Seder you're least ready for because you've just come out of all the prep. And that's rife with symbolism right there.)
And then they were asked if they wanted Torah.
Why should they say yes?
Bnei Yisrael were used to analyzing & examining ideas, not blindly swallowing all sorts of philosophies.
Remember, at the point of redemption, they'd encountered all different cultures and theologies of ancient Mesopotamia for around half a millennia, starting with Avraham Avinu.
The reason they said yes was because of their overwhelming gratitude toward Hashem.
They'd been eating lechem ha'oni (the bread of affliction) and all that symbolizes for so very long.
Then all of the sudden, they're marching out of Mitzrayim carrying gold & silver while the Egyptians are burying their dead.
As Rav Miller describes it (page 16):
We can’t even imagine the exhilaration of that time!
The Bnei Yisroel are marching out now in finery and in jewelry, and they’re so overwhelmed with gratitude to Hashem that they’ll do anything for Him.
"We finally got rid of this whole mess — Pharaoh and his regime and the whole caboodle."
And they said ברוך שפטרני and fell into the arms of Hakodosh Boruch Hu.
The Real You
Whether you are a doctor or a street peddler, those are just side jobs.
You real role is that of a Jew.
And Rav Miller also reminds us that in the natural way of things, slaves usually get lost in society. Often, they become the lowest classes of society even after their slavery ends.
Not every single individual, but in general.
We could have gotten lost forever in Mitzrayim.
And according to the natural way of the world, we should have gotten lost forever.
But we didn't.
Instead, Hashem raised us up to be a Mamlechet Kohanim (a Kingdom of Priests).
Yishtabach Shemo Forever.