The gemara (Shabbos 55b, Bava Basra 17a) names four people who didn't sin, and only died because the original snake got Chava and Adam to choose mortality. Meaning, they must have performed every obligation that came their way as well as avoiding every prohibition.
תָּנוּ רַבָּנַן אַרְבָּעָה מֵתוּ בְּעֶטְיוֹ שֶׁל נָחָשׁ וְאֵלּוּ הֵן בִּנְיָמִין בֶּן יַעֲקֹב וְעַמְרָם אֲבִי מֹשֶׁה וְיִשַׁי אֲבִי דָּוִד וְכִלְאָב בֶּן דָּוִד
The Sages taught [in a beraisa]: There were four people who died [only] because of the advice of the snake. And they are: Binyamin, son of Jacob; Amram, father of Moshe; Yishai, father of David; and Khileav, son of David.
Commentaries discuss whether this list is exhaustive, four people in all of history, or if the intent is that of all the people in Tanakh, only these four. It seems clear that the overwhelming majority of people don't perfectly keep all of halakhah. Including Avraham, Yitzchaq, Yaaqov, Sarah, Rivqa, Moshe, Aharon, Miryam, David... All of the major figures in history became who they were despite their less-than-perfect observance.
For that matter, the gemara appears to emphasize the point by naming each of the four in terms of how they relate to someone else. The gemara's target audience knows who Binyamin, Amram, Yishai and Khiliav were. (Even if I personally didn't recognize that last one.) But Amram isn't just Amram, he is "Amram, Moshe's father". And "Yishai, David's father". (The use of "ben" is less startling, but still in these cases, redundant. There is only one default "Binyamin" and only one "Khiliav" in Tanakh.)
One can only conclude (as other answers said), our job isn't perfect observance.
To give you an idea just how out of reach that is, there is this mitzvah (Shabbos 133b):
אַבָּא שָׁאוּל אוֹמֵר: ״וְאַנְוֵהוּ״ — הֱוֵי דּוֹמֶה לוֹ, מָה הוּא חַנּוּן וְרַחוּם — אַף אַתָּה הֱיֵה חַנּוּן וְרַחוּם.
Aba Shaul would say: "Ve'anveihu" ["and I will glorify him", to be reread "ve'ani-veHu -- and I and He"] -- become like Him. Just as He is Gracious and Compassionate, so too you should be Gracious and Compassionate.
I think we can agree at the outset that no human is ever going to perfectly emulate the Divine. We're limited; Hashem isn't.
So what does this mitzvah mean? And how did (e.g.) the Avos or Moshe did succeed in ways their perfectly observant family members did not?
The Kotzker Rebbe once asked his students: There are two people on a ladder, one on the fourth rung, and another on the 10th, which one is higher?
The book where I saw this thought doesn’t record his students’ answers. I assume some recognized it as a trick question, and answered that it was the one on the fourth, some answered the 10th figuring the rebbe was leading them somewhere, and others were silent. But the rebbe’s answer was succinct, “It depends who is climbing the ladder, and who is going down.”
Once I told the story, the idea was likely familiar. The idea of spirituality is not where you are, as that is largely a function of forces beyond your control (your upbringing, your genetics, etc…) Rather, it’s the direction you’re heading in, and how rapidly you’re getting there. To apply a notion from Kierkegaard, it’s not about being a good Jew, it’s about the process of becoming one. The journey, not the destination, is what matters.
This should be clear when we look at the mitzvah of emulating G-d. We are never going to get to the end state, behaving exactly like Hashem. No matter how far we go, we're still only an infinitesimal fraction of the way there. Our job is to keep on working to get there. The one way in which we can be like Hashem is by not being what we were made to be, but to keep on becoming what we choose. The most transcendent thing about humanity is our very ability to transcend.
Holiness is measured by our engagement in becoming, so why do we think of teshuvah, repentance, in terms of who to be by Yom Kippur? My dream that this would be “The Year” I finally get in gear was my deciding to be someone new. Teshuvah as motion, getting from point A to the desired point B. Fighting motion is always inertia, and this dream was really my expecting to shift that on the proverbial dime. Expecting sudden relocation to get to that point B is as unreliable as setting oneself a destination without planning the journey.
A different metaphor: teshuvah as acceleration – changing the direction and speed we’re taking in our lives, changing the course of life’s journey to aim for that “point B”, rather than simply expecting to leap there. Not “getting there” by Yom Kippur, but turning to head toward the right direction, and taking more effort to pick up speed.
Wow, that ended up longer than I thought it would be! I hope, though, it helped dispel some of the feeling of being overwhelmed, keeps away despair, and gives you ideas planning a next step.
See also my answer to "Being punished for things beyond bechira point", which involves the need to gradually move what Rav Dessler calls the nequdas habekhirah, the "decision point". The place where the desire to do the right thing and the wrong one battle, and the decision gets conscious attention and therefore fully subject to free will.
With each good decision, we habituate ourselves with doing the right thing. We move our "comfort zone". And thus move the nequdas habechirah. And since we are primarily judged for the decisions we make of our own free will, the result is that judgement revolves on which direction that point is moving, not on where it is.