Mishnah Chagigah 3:8:
כָּל הַכֵּלִים שֶׁהָיוּ בַמִּקְדָּשׁ, יֵשׁ לָהֶם שְׁנִיִּים וּשְׁלִישִׁים, שֶׁאִם נִטְמְאוּ הָרִאשׁוֹנִים, יָבִיאוּ שְׁנִיִּים תַּחְתֵּיהֶן.
All the vessels that were in the Temple had seconds and thirds for if the first became impure they would bring the second in its place.
The traditional understanding is that the Temple is the place where heaven and earth meet, indeed this is what Jacob sensed when he woke up from his dream and saw angels going up and down a ladder, between heaven and earth (Bereishit 28:17)
וַיִּירָא֙ וַיֹּאמַ֔ר מַה־נּוֹרָ֖א הַמָּק֣וֹם הַזֶּ֑ה אֵ֣ין זֶ֗ה כִּ֚י
אִם־בֵּ֣ית אֱלֹהִ֔ים וְזֶ֖ה שַׁ֥עַר ...
According to the Gemara (Eruvin 103) and Rambam (Kli HaMikdash 10:8), something smaller than 3x3 (tefachim) is not a beged if shelo bmokom begadim (not in place regularly clothed):
מר רב יהודה בריה דרבי חייא, לא שנואלא גמי, אבל צלצול קטן -הוי יתור
בגדים. ורבי יוחנן אמר: לא אמרו יתור בגדים אלא במקום בגדים, אבל שלא
במקום בגדים -לא הוי ...
There could be another explanation. Rambam in Hilchos Beis Habdhira says that the Altar was not a building, but one of the tools, used in the Temple (just like the Menorah or the table).
As such it is exempt from the railings because it is not a building to start with, like building a giant chair.
A number of Rishonim believe that the Aron / Kaporet represent G-d's Throne.
Ibn Ezra Shemot 25:22:
על כן הארון דמות כסא.
Thus the Aron is the form of a throne.
Ramban Shemot 25:21:
כי בעבור שיצוה בכרובים להיותם פורשי כנפים למעלה, ולא אמר למה יעשם כלל, ומה שישמשו במשכן, ולמה יהיו בענין הזה, לכך אמר עתה ונתת הכפרת עם כרוביו, שהכל דבר אחד על ...
This was also the opinion of Rav Avraham Yitzchak HaKohein Kook (1865-1935). I remember reading about this in Simcha Raz's biography on Rav Kook, titled "An Angel Among Men."
Can't find my copy of the book, but found the same idea attributed to Rav Kook in a Times Of Israel article: (among other results)
According to Rabbi Kook, the process of national ...
If Esav hadn't gone out and vigorously worshipped idols, murderded a man, and commited adultery on the day of his grandfather Abraham's funeral, then he wouldn't have been famished enough to sell his birthright for a bowl of red lentils and would have gone on to marry Leah and father half of the Tribes of Israel (if that is even the correct term!)
There are midrashim (I learned this through a series by Rabbi David Fohrman) which suggest that Sarah's harsh treatment of Hagar (though Hagar fully deserved it) led to the Jewish people being enslaved in Egypt.
On a more pshat level, you could also look at Yosef bragging about his dreams as leading to the Jewish people being enslaved in Egypt, the 10 ...